docs: def coalescence_times(self, backward=True):
          '''Generator over the times of successive coalescence events
  
          Args:
              ``backward`` (``bool``): ``True`` to go backward in time (i.e., leaves to root), otherwise ``False``
          '''
          if not isinstance(backward, bool):
              raise TypeError("backward must be a bool")
          for dist in sorted((d for n,d in self.distances_from_root() if len(n.children) > 1), reverse=backward):
              yield dist